Colouring effect

Gonnet, J.R, Colour effects of co-pigmentation of anthocyanins revisited. 1. A colorimetric definition using the CIELAB scale. Food Chem., 63, 409, 1998. 

Thus, although the colour of sparks is dependent upon flame temperature and may be similar to that of black body radiation, the overall colour effect can include contributions from atomic line emissions, from metals (seen in the UV and visible regions of the electromagnetic spectrum), from band emissions from excited oxide molecules (seen in the UV, visible and IR regions) and from continuum hot body radiation and other luminescence effects. So far as black body radiation is concerned, the colour is known to change from red (500 °C glowing cooker... 

Iridescence in many of the fabrics that are available commercially is basically a two-colour effect due to the absorption of light from dyes in two differently coloured yam bundles, constructed in such a way that the reflected light comes from one particular bundle in one direction and from another in a different direction. Whilst this is not truly iridescence it is a useful effect, but the process is very limiting on the construction of the fabric. 

Gonnet, J.-F., Colour effects of co-pigmentation of anthocyanin revisited — 3. A further description using CIELAB differences and assessment of matched colours using the CMC model. Food Chem., 75, 473, 2001. 

Where indigo and another dyestuff are present, it is sometimes necessary —besides estimating the indigo—to determine the relative colour effects due to the indigo and to the other colouring matter,1 and also to identify the latter and measure its fastness to light, washing, etc... 

Cellulosics could be moulded and extruded, and were employed in forms such as transparent or translucent tubes for packaging, and in multi-coloured effects for objects such as the barrels of fountain pens. Transparent tubes of high quality still are produced for use in packaging today. 

It is obvious here to think of an interaction of the Debye type of the appreciable moment of the nitro or carbonyl group with the readily polarizable unsaturated C — C bond in the unsaturated hydrocarbons or with the likewise readily polarizable free electron pair in the amines, etc. Actually the stability increases with increasing polarizability, compare for example, the heat of formation of j-trinitrobenzene with, respectively, benzene, naphthalene and anthracene AH 0.6, 3.4 and 4.4 kcal. In the series mono-, di- and tri-nitro-benzene with acenaphthene AH also increases with increasing number of partial moments, namely AH — o, 1.35 and 2.45 kcal. Nevertheless this explanation is inadequate, nitromethane with a moment [x = 3.54 D gives very much less stable compounds than nitrobenzene with (X = 4,22 D, while nitrosobenzene with [x =3.2 D gives stronger colour effects than nitrobenzene. 

Ferroxyl.—An effective method of showing that differences of potential exist between different parts of a piece of iron consists in utilising the ferroxyl indicator devised jointly by Cushman1 and Walker.2 A 1 5 per cent, solution of agar-agar jelly is prepared, a few drops of phenolphthalein added, and the whole rendered perfectly neutral whilst hot by titration either with alkali or acid as occasion requires. A small quantity of potassium ferricyanide solution is now added, and the solution poured into a shallow dish to cool. A clean sample of iron is placed on the solidified jelly and covered with a layer of warm solution, and the whole allowed to cool. After a few hours some very beautiful colour effects will have developed, and may be preserved for several months by keeping the surface of the agar covered with alcohol. 

Peyote Visions My first vivid show of mescal colour effects came quickly. 1 saw the stars, and then, of a sudden, here and there delicate... 

There are also serious side effects to fabric physical properties from flame-retardant finishing that must be recognised, often caused by the high application levels of the flame retardants. Harsh hand, loss of tensile suength and colour effects (fabric yellowing and dye shade changes) are common problems with durable flame-retardant finishes for cotton. The combination with other finishes, such as softeners, easy-care and repellent finishes, must be carefully tested. The flame retardancy of the multi-purpose finish is more often reduced than it is acceptable. 

Various colour effects are obtained by the addition of reducing agents to solutions of molybdenum compounds. Zinc in the presence of acid, and stannous chloride, produce colours changing from blue to green, brown, and yellow. Sulphur dioxide produces a Huish-green coloration or precipitate according to the amount of molybdenum present. A... 

Thompson and Gratton discuss various technical aspects of the phase shift fluorometric method for determining lifetimes. Rayleigh scattering shows apparent colour effects due to the wavelength dependence of electron transit times in the PM tube. 

A simple qualitative explanation of the colour effects of Me4Sb2 and Me4Bi2 is based on the assumption of p orbital overlap in the bismuth or antimony chains (Figure 3). The transition energy between the orbitals in the monomers is larger than the band gap in the polymer and thus the bathochromic shift of the edge of absorption between monomers in... 

The isolobal relations R E RE and RE E " (E" = Sb,Bi E " = Se,Te) that are supported by the thermochromic properties of some ditellurides have stimulated the search for colour effects of compounds with bonds between Sb, Bi and Se or Te. As a result of these efforts, knowledge in synthetic chemistry in the field has expanded considerably and methods have been developed for the preparation of the following types of novel compounds - - ... 

Zirconium-silicate refractories have found successful application in certain parts of glass furnaces, in particular those for borosilicate and fluoride glasses (tank, feeder, throat). Refractories based on Cr203 have recently been employed at the critical points of glass tanks. This oxide show s the best resistance to glass-contact corrosion but its application is limited by its colouring effect. 

A brown colour is similarly achieved by the combination of Fe203 + MnO, but in a ratio of 1 2 to 1 3, or more frequently by the colouring effect of small amounts of iron and sulphur (the so-called amber glass, cf. Chapter II, Section 3.1). The... 

These comprise, on the one hand, easily combustible substances such as charcoal, sulphur, antimony sulphide, resins, and tar and on the other hand, they include substances which readily give up oxygen and support combustion, such as saltpetre (potassium nitrate), and potassium chlorate or other chlorates. A third category includes those substances used for the various colour effects (barium strontium, copper, and other salts), and also finely divided metals, and coarse particles of charcoal to cause sparks and showers of fire ( golden rain and the like). Other substances are sometimes used to decrease the rate of burning and to increase brilliance (r.g. mercurous chloride and mercuric thiocyanate). 

Fig. 34 Colour effects of copolymer P23 at pH 1 (no shift) and at pH 10 (bathochromic shift)...

Main components 0.4-1% essential oil, which contains app. 50% of the odour carrier safranal. For further components of the oil see [258, 259[. Safranal is formed by hydrolysis from the glycoside picrocrocin, which causes the bitter taste. Carotinoids, mainly the water-soluble crocin (crocetin digentiobiose ester) and other crocetin derivatives [260[, a- and P-carotin, zeaxanthin and lycopin are responsible for the colouring effect. 

Riboflavin (also known as vitamin B2) is often used, for example, in energy drinks, as it is valued not only for its yellow colouring effect, but also for its positive properties as a functional ingredient. 

Citrus oil is a natural flavouring derived from citrus peel that has a colouring effect with a light yellow shade. 

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